Spark plug



Patented Feb. i9, 1924.'

lunire) l STATES i AUGUST W. orELn'r, or WEST HOBOKENQNEWI JERSEY'.

eraan PLUG.

" Application filed October 24, 1921. Serial No. 510,120.

T0 zalf w'iomt may concern.:

Be it known that I, A UGUs'r IVOFELDT,

a citizen of-fthe United States, residing at Test Hoboken, in the county of Hudson and State of New Jersey, haveinyented certain' new and useful Improvements in Spark Plugs, of which the following isa clear and exact specification, reference being had to the drawiings which form a part of the specification. i

This invention relates to spark plugs and my improvement is directed'to a plug structure wherein means are provided for establishing a highly heated zone in the vicinity of the electrodes to ensure combustion of the oil and fuel which would otherwise tend to collect in that region and form carbonaceous deposits, with the deleterious effect of short circuiting the flow of current.

The provision of a pocket or chamber in a plug behind the spark gap is well known to the art, and the expansion which occurs therein is useful in that oilV and residual fuel are discharged, and the electrodes cleaned thereby; 'but this action is most eflicient when the engine is running at high speed or under heavy loads.

When the engine is starting up or while idling, with the jacket water keeping the temperature down, the walls of the plug chamber may not become sufficiently hot to permit complete combustion of the oil and fuel, because the heat of combustion is too quickly absorbed by the cooling system,

and it is at such times that carbonizationV occurs. It is therefore one of the purposes of my invention to provide means for preserving*r the heat of combustion in the spark plug chamber under all conditions of motor operation, so that complete combustion may occur therein, thus preventing the formation of carbon deposits.

This result. is accomplished through my invention by the provision of an extremely thin cylindrical wall for the interior of the plug chamber, and surrounding this wall with an air space to serve as an efficient heat insulation, so that the wall will be capable of quickly absorbing the heat of thel explosions, and, by reason ofthe external l insulation, this heat will be concentrated In the drawing.:- Y

Figure 1 is a sectionalv elevation of my` improved spark plug,xas applied.` .Y ,y Fig. 2*.is a detail -of the flanged sleevewhich coacts with the inner surface of the shell to constitute an insulating air space.v

Fig.V 3 is a detail Vof the packing ring.:

Fig. 4 is a detailof the cap electrode, and -Y Fig. 'is a detail of thesecuring ring. j In the'drawings, let 1 indicate the porcelain in which is axially fitted .the central electrode 2, the porcelain having the usual shouldered portion 3, which engages within the threaded shell 4, these parts beingof well known character..

A. packing ring 5 lies between the porcelain and shell 4,' and is pressed against the shoulder 3 of the porcelain by a sleeve 6, which is provided with the external flanges 7, 8, that are located respectively at its opposite ends.

There is thus provided lan annular air space `9 between the sleeve 6 and the inner surface of shell 4, this space being bounded at its ends by the flanges 7 and 8.

The other electrode 10 is in the form of a concavo-convex cap, with a. central orifice 11 to present its edge in spark-gap relation with electrode 2. The cap 10` has a radial flange 12 whereby it lies against the outward flange 8 of sleeve 6, and the parts are secured within the shell by a threaded ring 13 which is screwed into the forward end of the shell and bears against the flange 12. y

It should be noted thatthe wall of sleeve 6, between the flanges 7, 8 is of extremely thin material, in order that it may have the quality of rapid heat absorption; also that the 'space 9, being an air space, serves as a highly efficient insulator to .prevent loss of heat by radiation from the plug chamber.

Similarly the cap electrode 10 is of thin material in order that it too may possess the quality of rapid heat absorption,to aid in maintaining a high temperature withinthe plug chamber. Y

By these means the oil which enters thev plug chamber is either consumed therein or is held in suchfluid state as to prevent the formation therefrom of carbonaceous deposits upon and about the porcelain or other insulation member, and also the fuel mixture which enters the plug chamber becomes either entirely consumed or its residue held in such free state that it, together with any 1. A spark plug comprisinga shell, an insulation member therein having la recess in its forward portion, a central electrode carried by the insulation memberandextendy lng out through the recess, an apertured cap electrode in spark` gap relation with the central eleotrode, and a sleeve disposed concentrically between the recessed portion of the insulation member and the shell, the sleeve having external end flanges which coact With the shell in the provision of an annular air space, to prevent heat radiation'and'thereby maintain a high Ytemperature Within and about the insulation Vmember.

2. A spark plug comprising a shell, an insulation member thereinjhaving-a rrecess in its forward portion, a central electrode carried by the insulation member and extending out through the recessan apertured cap Y electrode in spark gap relation With the central electrode and having' av radial flange, a sleeve disposed concentrically between the recessed'portion of :the insulation member and the shell, the sleeve having external end flanges which coact with the shell Vin the pro#V vision of an annular air space, to prevent heat radiation and thereby maintain a high temperature in vandv about the insulation member, and a ring lto t Within'the'shell end, olampingfthe jcap flange against the outer flange of the sleeve. Y Y i "Signed at "New York, in the county and State `of New York, this 20th day of October, 1921. Y. Y i i AUGUST W.' @FELDT. [L.S 

